1. Field of the Invention
This invention relates to a heat transfer recording apparatus and a facsimile apparatus for transferring the ink of an ink sheet to a recording medium to thereby effect the recording of images on the recording medium.
The term "heat transfer recording apparatus" used herein covers, besides a facsimile apparatus, for example, what assumes the form of an electronic typewriter, a copying apparatus and a printer.
2. Related Background Art
Generally, a heat transfer printer uses an ink sheet comprising base film having heat-meltable (or heat-sublimating) ink applied thereto, selectively heats the ink sheet correspondingly to an image signal by a thermal head, and transfers the melted (or sublimated) ink to a recording sheet to thereby accomplish image recording. Generally, this ink sheet is one from which the ink is completely transferred to a recording sheet by one time image recording (a so-called one-time ink sheet) and therefore, it has been necessary that after the termination of the recording of one character or one line, the ink sheet be conveyed by an amount corresponding to the recorded length, and then the unused portion of the ink sheet be reliably brought to the recording position. This has increased the quantity of ink sheet used, and as compared with an ordinary thermosensitive printer for recording images on thermosensitive paper, the heat transfer printer has suffered from the tendency of its running cost becoming higher.
In order to solve such a problem, there has been proposed a heat transfer printer in which as seen in U.S. Pat. No. 4,456,392, Japanese Laid-Open Patent Application No. 58-201686 and Japanese Patent Publication No. 62-58917, a recording sheet and an ink sheet are conveyed with a velocity difference therebetween. As described in these publications, there is known an ink sheet capable of plural (m) times of image recording (a so-called multiprint sheet). If such ink sheet is used, when recording is to be continuously effected over a recording length L, recording can be accomplished with the length of the ink sheet conveyed after or during the recording of each image being made smaller than the length L (L/n:n&gt;1). Thereby, the efficiency of use of the ink sheet becomes n times as great as that before, and a reduction in the running cost of the heat transfer printer can be expected. This recording system will hereinafter be referred to as multiprint.
In the case of multiprint using such an ink sheet, the ink of the ink layer of the ink sheet is heated n times. During each cycle of heating, a shearing force is produced between that portion of the ink of the ink layer which has been melted (or sublimated) and that portion of the ink which is not melted (or sublimated) to thereby transfer the ink to the recording sheet. This has led to the problem that for example, even when true recording is effected with the recording sheet and the ink sheet being stationary, the ink of the ink sheet may not sufficiently be transferred to the recording sheet.